1. Field of the Invention
This invention relates generally to manufacturing systems. More particularly, this invention relates to computer integrated manufacturing systems that dynamically dispatches product lots for fabrication to subsequent equipment in a manufacturing line.
2. Description of Related Art
In competitive manufacturing environments such as fabrication of electronic integrated circuits on substrates, delivery to a committed schedule is one of the most important factors to the operation of the enterprise. However, the tool utilization and quality of the fabrication of the product are almost equally important. The balancing of the loading of equipment or tooling of the various stages of the manufacturing lines of the enterprise must be considered.
Often to accommodate a “hot lot” or a lot having a very high priority for fabrication, the necessary manufacturing equipment may be idled or have its scheduling minimized to allow acceptance of the “hot lot” upon arrival. In other instances, the operators may not have a complete understanding of the flow of the product through the manufacturing line and may cause certain equipment to lack product lots for processing or may cause other equipment to have a backlog or long queue of product waiting for the equipment. Supervisors generally observe multiple units or pieces of manufacturing equipment within the manufacturing line and are able to determine if there is no queue or a too long a queue for individual pieces of equipment. The supervisors then communicate changes in the priorities of the lots set for processing in an attempt to adjust the distribution of the queues of the manufacturing equipment.
The operators must then interpret the instructions of the supervisors to attempt to adjust the distribution of the product lots for processing. Often there is a misunderstanding or miscommunication between an operator and the supervisor or the operator makes a mistake in the operation of the equipment. The operator does not react quickly to the instruction or does not comprehend the instructions and the fabrication of the product is further delayed.
U.S. Pat. No. 6,564,113 (Barto, et al.), describes a Lot start agent that calculates virtual WIP time in a multi-product and multi-bottleneck manufacturing environment. A system and method are provided for calculating virtual WIP time (“VWIP”). The system and method provide for the calculation of one or more bottleneck VWIP values.
U.S. Pat. No. 6,470,227 (Rangachari, et al.), describes a method and the apparatus for automating a microelectric manufacturing process by configuring application objects that implement a domain knowledge for a piece of equipment and then implementing a workflow. The method is embodied in a computer program that is part of a computer system
U.S. Pat. No. 6,259,959 (Martin) describes a method for determining the performance components of a manufacturing line. A process for optimizing a manufacturing line including raw processing times of a plurality of work centers; summing the work center raw processing times, determining work center cycle times, dividing the work center cycle times by respective ones.
U.S. Pat. No. 6,128,588 (Chacon) describes an integrated wafer fab time standard (machine tact) database An integrated wafer fab production characterization and scheduling system incorporates a manufacturing execution system with a scheduling system based on simulation. The system provides a simulation tool integrated with the manufacturing execution system to evaluate proposed production control logic. Also included are: integration of preventive maintenance scheduling, Kanban based WIP control, an integrated time standard database, and real time lot move updates.
U.S. Pat. No. 5,826,238 (Chen, et al.) describes a method and system that operates a data processing system. This includes a data base computer system and a resource allocation computer for control of resource allocation. The method has several steps including: deriving data from the storage means and computing the targets for each of the stages; obtaining machine capacity data from the data storage means and employing the machine capacity data for allocating machine capacity proportionally and adjusting targets.
U.S. Pat. No. 5,768,133 (Chen, et al.) describes a WIP/move management tool for semiconductor manufacturing plant and method of operation thereof. This interactive data processing system and/or method is a management tool for a manufacturing plant including a shop floor control system. A server contains a data engine for extracting data, a load and transform data unit, and a database management storage unit. The database management storage unit supplies data to an interactive graphic user interface.